The invention relates to a device for automatic implementation of chemical or biological methods, more particularly for sequencing and amplifying nucleic acid sequences, including a pipette apparatus and a thermocycler, the pipette apparatus comprising a pipette arm for pipetting sample substances and/or chemicals.
U.S. Pat. No. 5,443,791 discloses a device for implementing chemical or biological methods which comprises several workstations. These workstations are, among others, a thermocycler, an actively cooled enzyme storage station, a wash station, a reagent storage station and a DNA sample station. In this known device a pipette tip is moved in a plane parallel to the worksurface to implement a liquid transfer. The reaction vessels of this device are configured as dished cavities in a metal block arranged in the thermocycler. The individual reagents are first pipetted in one of the reaction vessels located in the thermocycler and then subjected to a temperature profile. Before a further reaction can be carried out the reaction vessel(s) need to be cleaned. Should cleaning fail to be total, subsequent reactions are contaminated which in highly sensitive methods such as the PCR method is a very serious drawback. In addition to this it is of disadvantage that the reaction vessels are configured as dished cavities in a metal block which come into direct contact with the reagents. Metal surfaces cannot always be cleaned totally free of any remainders at reasonable expense and thus form a further source of contamination.
Using thermocyclers enables predetermined temperature profiles to be instrumented. Thermocyclers are used more particularly in gene technology for sequencing and amplifying nucleic acid sequences. Such methods are described e.g. in EP 200 362 B1, EP 258 017 B1 and EP 201 184 B1.
Known from DE 44 12 286 A1 is a system for closing off samples vessels by means of covers. This system comprises a means for opening and closing reaction vessels able to grip and relocate a cover by means of a latching mechanism.
The invention is based on the object of sophisticating a device of the aforementioned kind such that it is suitable for automatic implementation of chemical or biological methods, more particularly for sequencing and amplifying nucleic acid sequences with no contamination.
This object is achieved by a device having the features of claim 1. Advantageous aspects read from the sub-claims.
The invention is characterized in that the pipette apparatus and the thermocycler are configured as spatially separated workstations and that a handling arm for moving at least one sample vessel containing sample substances or chemicals and configured separate from the workstations is provided.
Spatially separating the pipette apparatus and thermocycler and providing reaction vessels configured independent of the workstations, whereby the reaction vessels are moved by a handling arm between the individual workstations, permits fully automated implementation of complex chemical and biological methods with a high thruput since reaction vessels are simultaneously located in the pipette apparatus and in the thermocycler and correspondingly worked without necessitating any complicated cleaning procedures on the device. This enables complex methods working more particularly with totally different reagents and sample substances to be implemented fully automated practically simultaneously and/or in sequence.
The device in accordance with the invention thus enables complex chemical and biological methods, more particularly sequencing and amplifying nucleic acid sequences to be implemented fully automated and free of contamination. Thus greatly simplifying and significantly enhancing accuracy and safety in the working procedures.
The embodiment as it reads from claim 3 including a multi-tasking controller permits robotic handling of various sample substances, applications etc simultaneously without a laboratory worker being needed for monitoring and checking the individual steps in the process, as a result of which, even the most complex method profiles can now be implemented in a minimum space environment with no risk of error due to mistakes in siting or the like.
A further preferred embodiment of the device in accordance with the invention comprises a means for automatically opening and closing sample vessels by means of covers. It is usual in automated devices that the sample vessel is closed off by a film of wax or oil. Closing it off in this way is popular in manual implementation of chemical or biological reactions. Making use of covers releasably secured to the vessels has salient benefits in automated operation as compared to the conventional use of wax or oil films. Thus, a vessel once filled with reagents and/or sample substances and closed off with a cover can be reopened and additional reagents and sample substances added. The reagents and sample substances are introduced into the reaction vessel by means of a pipette tip held just above the liquid surface in the reaction vessel so that there no contact between the pipette tip and the reagents and sample substances contained in the reaction vessel to thus reliably prevent cross-contamination by the transfer of reagents and sample substances from one reaction vessel to the other.
In conventionally sealing the reaction vessels the pipette tip needs to penetrate the wax or oil film during pipetting and to dip into the liquid contained in the reaction vessel. Before applying the pipette tip to a further reaction vessel e.g. the same substance, the pipette tip needs to be cleaned or replaced. This is usual in manual implementation of chemical and biological reactions, it adding to the time and costs needed in implementing the reactions fully automated.
When movements occur in the liquid contained in the reaction vessel or movements of the reaction vessel itself or delayed boiling during a heating phase in the thermocycler such an oil or wax film cannot reliably prevent liquid from escaping from the reaction vessel and e.g. slosh-contaminating a neighboring reaction vessel.
In addition to this, sealing with wax has the disadvantage that this solidifies when cooled to low temperatures (e.g. 14xc2x0 C.) and obstructs further treatment.